2.7.1. MTT assay
MTT assay was used to study the proliferation potential and survival of adipose-derived mesenchymal stem cells (ADMSCs) on different substrates. After plasma processing, scaffolds were cut into disks (11 mm diameter) and sterilized with 70% ethanol and ultraviolet light exposure (40 minutes and 120000 µ J/CM2). After being placed in the culture medium overnight, the cells were seeded on the samples at a density of 5 × 103 cells/sample, and then incubated in 5% CO2 at 37 °C in high glucose Dulbecco’s modified Eagles medium, DMEM, supplemented with 10% fetal bovine serum, FBS, and 1% penicillin-streptomycin. The cytotoxicity value of the prepared scaffold (PCL and G3-SPION-PCL ) was evaluated using MTT assay on days 1, 3, 7, and 14 after the seeding of ADMSCs cells and compared to the tissue culture plates (TCP), as control. The samples were washed with PBS and incubated in 10% V/V MTT in a DMEM solution at 37 °C for three h. (Esmaeili, Soleimani, et al., 2019) After the formation of the formazan crystals inside the cells seeded on the scaffolds, Then, the supernatant was removed, DMSO was added to dissolve the Formosan crystals, and the absorbance of the purple solution was measured at 570 nm in a microplate reader (BioTek, ELX800, USA).